From: Eric Sandeen <sandeen@sgi.com>
Date: Tue, 22 Jan 2002 19:03:35 +0000 (+0000)
Subject: Reduce XFS_MAX_FILE_OFFSET to something Linux can handle
X-Git-Tag: v2.0.0~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1f9cea3993eea566a8f4a4909497fdbd20b9a4c4;p=thirdparty%2Fxfsprogs-dev.git

Reduce XFS_MAX_FILE_OFFSET to something Linux can handle
---

diff --git a/include/xfs_inode.h b/include/xfs_inode.h
index 35be1e3ba..40b90568a 100644
--- a/include/xfs_inode.h
+++ b/include/xfs_inode.h
@@ -457,15 +457,18 @@ void xfs_ifork_next_set(xfs_inode_t *ip, int w, int n);
 #define	XFS_ITRUNC_MAYBE	0x2
 
 /*
- * Maximum file size.
- * if XFS_BIG_FILES 2^63 - 1 (largest positive value of xfs_fsize_t)
+ * if XFS_BIG_FILES, 2^(32+PAGE_SHIFT) - 1 (due to linux page cache),
  * else 2^40 - 1 (40=31+9) (might be an int holding a block #)
- * Note, we allow seeks to this offset, although you can't read or write.
  * For the not XFS_BIG_FILES case, the value could be 1 higher but we don't
  * do that, for symmetry.
+ *
+ * NOTE: XFS itself can handle 2^63 - 1 (largest positive value of xfs_fsize_t)
+ * but Linux can't go above 2^(32+PAGE_SHIFT)-1: the Linux VM uses a 32 bit
+ * page number index to index cache data, so 2^32 * PAGE_SIZE is as big as 
+ * you can go.
  */
 #if XFS_BIG_FILES
-#define XFS_MAX_FILE_OFFSET	((long long)((1ULL<<63)-1ULL))
+#define XFS_MAX_FILE_OFFSET	((long long)((1ULL<<(32+PAGE_SHIFT))-1ULL))
 #else
 #define	XFS_MAX_FILE_OFFSET	((1LL<<40)-1LL)
 #endif